using System;

using Org.BouncyCastle.Asn1;

namespace Org.BouncyCastle.Asn1.Cms
{
	public class RecipientKeyIdentifier
		: Asn1Encodable
	{
		private Asn1OctetString      subjectKeyIdentifier;
		private DerGeneralizedTime   date;
		private OtherKeyAttribute    other;

		public RecipientKeyIdentifier(
			Asn1OctetString         subjectKeyIdentifier,
			DerGeneralizedTime      date,
			OtherKeyAttribute       other)
		{
			this.subjectKeyIdentifier = subjectKeyIdentifier;
			this.date = date;
			this.other = other;
		}
		
		public RecipientKeyIdentifier(
			byte[] subjectKeyIdentifier)
			: this(subjectKeyIdentifier, null, null)
		{
		}

		public RecipientKeyIdentifier(
			byte[]				subjectKeyIdentifier,
			DerGeneralizedTime	date,
			OtherKeyAttribute	other)
		{
			this.subjectKeyIdentifier = new DerOctetString(subjectKeyIdentifier);
			this.date = date;
			this.other = other;
		}

		public RecipientKeyIdentifier(
			Asn1Sequence seq)
		{
			subjectKeyIdentifier = Asn1OctetString.GetInstance(
				seq[0]);

			switch(seq.Count)
			{
				case 1:
					break;
				case 2:
					if (seq[1] is DerGeneralizedTime)
					{
						date = (DerGeneralizedTime) seq[1];
					}
					else
					{
						other = OtherKeyAttribute.GetInstance(seq[2]);
					}
					break;
				case 3:
					date  = (DerGeneralizedTime) seq[1];
					other = OtherKeyAttribute.GetInstance(seq[2]);
					break;
				default:
					throw new ArgumentException("Invalid RecipientKeyIdentifier");
			}
		}

		/**
		 * return a RecipientKeyIdentifier object from a tagged object.
		 *
		 * @param _ato the tagged object holding the object we want.
		 * @param _explicit true if the object is meant to be explicitly
		 *              tagged false otherwise.
		 * @exception ArgumentException if the object held by the
		 *          tagged object cannot be converted.
		 */
		public static RecipientKeyIdentifier GetInstance(
			Asn1TaggedObject	ato,
			bool				explicitly)
		{
			return GetInstance(Asn1Sequence.GetInstance(ato, explicitly));
		}

		/**
		 * return a RecipientKeyIdentifier object from the given object.
		 *
		 * @param _obj the object we want converted.
		 * @exception ArgumentException if the object cannot be converted.
		 */
		public static RecipientKeyIdentifier GetInstance(
			object obj)
		{
			if (obj == null || obj is RecipientKeyIdentifier)
				return (RecipientKeyIdentifier) obj;

			if (obj is Asn1Sequence)
				return new RecipientKeyIdentifier((Asn1Sequence) obj);

			throw new ArgumentException("Invalid RecipientKeyIdentifier: " + obj.GetType().Name);
		}

		public Asn1OctetString SubjectKeyIdentifier
		{
			get { return subjectKeyIdentifier; }
		}

		public DerGeneralizedTime Date
		{
			get { return date; }
		}

		public OtherKeyAttribute OtherKeyAttribute
		{
			get { return other; }
		}

		/**
		 * Produce an object suitable for an Asn1OutputStream.
		 * <pre>
		 * RecipientKeyIdentifier ::= Sequence {
		 *     subjectKeyIdentifier SubjectKeyIdentifier,
		 *     date GeneralizedTime OPTIONAL,
		 *     other OtherKeyAttribute OPTIONAL
		 * }
		 *
		 * SubjectKeyIdentifier ::= OCTET STRING
		 * </pre>
		 */
		public override Asn1Object ToAsn1Object()
		{
			Asn1EncodableVector v = new Asn1EncodableVector(subjectKeyIdentifier);
			v.AddOptional(date, other);
			return new DerSequence(v);
		}
	}
}
